Implement basic USB device enumeration on Android.

content/app/android/library_loader_hooks.cc

Index: content/app/android/library_loader_hooks.cc
diff --git a/content/app/android/library_loader_hooks.cc b/content/app/android/library_loader_hooks.cc
index eae25373ae7ee67aff85d8a3bc2c5095650ea2a9..7936970c29cfb5e41867e4fd25859f49a9655b06 100644
--- a/content/app/android/library_loader_hooks.cc
+++ b/content/app/android/library_loader_hooks.cc
@@ -25,6 +25,7 @@
 #include "content/public/common/content_switches.h"
 #include "content/public/common/result_codes.h"
 #include "device/bluetooth/android/bluetooth_jni_registrar.h"
+#include "device/usb/android/usb_jni_registrar.h"
 #include "media/base/android/media_jni_registrar.h"
 #include "media/midi/midi_jni_registrar.h"
 #include "net/android/net_jni_registrar.h"
@@ -74,6 +75,9 @@ bool EnsureJniRegistered(JNIEnv* env) {
     if (!device::android::RegisterBluetoothJni(env))
       return false;
 
+    if (!device::android::RegisterUsbJni(env))
+      return false;
+
     if (!media::RegisterJni(env))
       return false;